Headlamps on motor vehicles require proper aiming, both vertically and horizontally, for safe and optimal performance. Accordingly, adjustment or “aiming” is performed before a vehicle is put into service and may be performed from time to time thereafter if vibration or other conditions or events move the headlamp away from optimal positioning. If the headlamp is not properly adjusted vertically, the light may be directed too close to the vehicle, not adequately illuminated more distant objects. Conversely, if the headlamp is aimed to direct the light too far in the distance, the area in front of the vehicle may not be properly illuminated for adequate recognition of something in front of the vehicle. Further, a headlamp aimed too distant may blind oncoming drivers even in the dimmed or low beam condition.
Proper horizontal adjustment is just as important as proper vertical adjustment. If the headlamp is aimed to direct the beam of light too far to the left, oncoming drivers can be blinded. If focused too far to the right, the primary field directly in front of the automobile may not be properly illuminated. Improperly directed headlamps can be distracting both to the operator of the vehicle and to other drivers approaching the vehicle.
It is known to provide headlamp assemblies adjustable about both vertical and horizontal axis with adjusters operated by screwdrivers or other implements for lengthening and shortening the adjuster to cause the headlamp assembly to pivot about the axis. Some known adjustment mechanisms are component style systems having individual components requiring assembly at the time of installation. Such adjusters can include bushings, bosses, O-rings and push nuts that need to be connected to a screw during installation. Although adjusters of this type have proven to be useful, because of the many individual components required, labor for assembly and installation are high. It is preferable to have a pre-assembled adjuster that can be installed quickly and easily in the headlamp assembly and be ready for immediate adjustment.
In some known adjuster configurations, an output shaft is operatively connected to a movable reflector in the headlamp assembly. Linear movement of the output shaft pivots the reflector to change the direction of light. One or several gears can be driven by screwdrivers or other implements for rotating mechanisms in the adjuster and causing linear movement of the output shaft. Problems and difficulties can be encountered if the adjuster is adjusted too far. If moved axially longer than intended, the headlamp assembly can be damaged or the adjuster can be damaged requiring repair or replacement. If withdrawn too far, the output shaft can become disengaged from its driving mechanisms, again causing difficulties and problems. When such occurs on an assembly line, assembly line output is adversely affected. If over adjustment occurs after the vehicle has been placed in use, access for repairing or replacing the adjustment mechanism can require significant disassembly and cost in time and expense. Placing axial restraints on the movement of the output shaft can result in damage to the drive mechanisms of the adjuster, particularly if powered tools are used for causing the adjustment.
What is needed is a headlamp adjusted that can tolerate over adjustment in either direction, without damage to the adjuster or to the headlamp assembly in which it is installed.